Rolled surfaces having a dulled gloss finish

ABSTRACT

This application discloses cold rolled surfaces having a dulled gloss finish. The finish has a fairly uniform glossiness with a slightly matted appearance and with minimal directionality. The surfaces are prepared from work rolls having an Ra value of from 0.2 to 0.4 μm and an Rz value of less than 3.0 μm. Methods of preparing the surfaces are also described herein.

PRIOR RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/788,637, filed Mar. 15, 2013, which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention provides rolled surfaces having a dulled glossfinish. The dulled gloss finish has a uniform glossiness with a slightlymatted appearance and with minimal directionality.

BACKGROUND

Surface finishes having a smooth surface are desirable for manymanufactured items. Reducing the roughness of a conventional groundsurface takes a long time and leads to an extreme sensitivity togrinding imperfections, so that the product can only be made onspecialized high-gloss mills. Any imperfection appears immediately andruins the product impression. Also, a residual directionality is oftenleft in the surface so that the product cannot easily be mixed withothers at different directions.

A matted surface, on the other hand, tends to be rougher and to lookvery grey. For many applications, the roughness is too great. Inaddition, the surfaces are difficult to produce and dirty, sinceroughened rolls tend to plough the surface and leave large amounts offines which hinder further processing unless cleaned. The smearingcaused by relative speeds between strip and work roll tends to limit thereductions and speeds that can be used in manufacture. Otherwise, anunusable surface will result.

SUMMARY

The present invention solves these problems by providing rolled surfaceshaving a dulled gloss finish. The dulled gloss finish as describedherein has a relatively uniform glossiness with a slightly mattedappearance and with minimal directionality. The dulled gloss finishdescribed herein combines the effect of an acceptable amount of glosswith the effect of uniform matting. By breaking off the roughness peakson the roll and replacing them with a controlled smoothness, the productis not susceptible to smearing of the rough parameters and generatingfines. The roughness also suppresses the tendency to be sensitive tominor imperfections in the gloss component. The surface is suitable forlithographic use and for can end use.

The surface of the work roll used for applying a dulled gloss finish ona metal substrate surface, as described herein, can have an Ra value offrom 0.15 to 0.4 μm (e.g., from 0.20 to 0.4) and an Rz value of lessthan 3.0 μm. Optionally, the surface of the work roll has an Ra value offrom 0.27 μm to 0.3 μm and an Rz value of less than 2.5 μm. The workroll can be a cold mill work roll.

A method of preparing a work roll for applying a dulled gloss finish ona metal substrate surface is also described herein. In one embodiment,the method includes the steps of roughening an unfinished work rollsurface to form a roughened work roll surface, wherein the roughenedwork roll has an Ra of 0.20 μm or less and an Rz of 2.00 μm or less;polishing the roughened work roll surface to form a polished work rollsurface having an Ra of less than 0.015 μm and an Rz of less than 0.25μm; uniformly roughening the polished work roll surface to form auniformly roughened work roll surface having an Ra of from 0.35 μm to0.45 μm and an Rz of less than 5 μm; and finishing the uniformlyroughened work roll surface to form a work roll surface, wherein thework roll surface has an Ra value of from 0.2 to 0.4 μm and an Rz valueof less than 3.0 μm. Work rolls prepared according to this method arealso described herein.

Further described herein are methods for forming a dulled gloss finishon a metal substrate. In one embodiment, the method includes the stepsof roughening an unfinished work roll surface to form a roughened workroll surface, wherein the roughened work roll has an Ra of 0.20 μm orless and an Rz of 2.00 μm or less; polishing the roughened work rollsurface to form a polished work roll surface having an Ra of less than0.015 μm and an Rz of less than 0.25 μm; uniformly roughening thepolished work roll surface to form a uniformly roughened work rollsurface having an Ra of from 0.35 μm to 0.45 μm and an Rz of less than 5μm; finishing the uniformly roughened work roll surface to form a workroll surface, wherein the work roll surface has an Ra value of from 0.2to 0.4 μm and an Rz value of less than 3.0 μm; inserting the work rollin a cold mill; and cold rolling the metal substrate with the work rollto achieve the dulled gloss finish on the metal substrate. Optionally,the metal substrate can be aluminum or an aluminum alloy sheet.Optionally, the metal substrate can be a steel sheet.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a picture showing the surface structure of the dulled glossfinish.

FIG. 2 is a picture showing the surface structure of the standard gritfinish.

FIG. 3 is a graph showing the 20° gloss levels of the bright rolledfinish, the dulled gloss finish (DGF), and the standard grit finishsamples. “CES” refers to can end stock.

FIG. 4 is a graph showing the 60° gloss levels of the bright rolledfinish, the dulled gloss finish (DGF), and the standard grit finishsamples.

FIG. 5 is a graph of the ratio of directions for the 20° and 60° glossreadings of the bright rolled finish, the dulled gloss finish (DGF), andthe standard grit finish samples.

FIG. 6 is a graph showing the 85° gloss levels of the bright rolledfinish, the dulled gloss finish (DGF), and the standard grit finishsamples.

FIG. 7 is a graph showing the confocal image calculations of surfaceisotropy for surfaces from the bright rolled finish, the dulled glossfinish (DGF), and the standard grit finish samples.

FIG. 8 is a graph showing the mean roughness (Sa) of the surfaces fromthe bright rolled finish, the dulled gloss finish (DGF), and thestandard grit finish samples.

FIG. 9 is a depiction of the second quartile area (i.e., the projectedareas above 50% height) for the bright rolled finish, the dulled glossfinish (DGF), and the standard grit finish samples.

FIG. 10 is a depiction of the surface height kurtosis for the brightrolled finish, the dulled gloss finish (DGF), and the standard gritfinish samples.

FIG. 11 is a graph showing the second quartile area against surfaceheight distribution kurtosis for the standard grit finish samples (leftfour diamonds above 10% projected area), the dulled gloss finish (DGF)samples (middle four diamonds below 6% projected area), and the brightrolled finish sample (right diamond between 10% and 11% projected area).

FIG. 12 contains panels showing confocal images of the samples. Panel(a) shows the bright finish; panel (b) shows DGF 2009 12; panel (c)shows DGF 2011 07 a; panel (d) shows DGF 2011 07 b; panel (e) shows DGFCES 2012 06 a; panel (f) shows DGF CES 2012 06 b; panel (g) shows DGF2009 10; panel (h) shows Rolled Grit Can End Stock (CES) 2011 07; andpanel (i) shows Rolled Grit CES Backside.

DETAILED DESCRIPTION

The present invention solves these problems by providing a dulled glosssurface finish for rolled products. “Dulled gloss” finish, as usedherein, refers to a finish having a relatively uniform glossiness with aslightly matted appearance. The dulled gloss finish can be characterizedas having an appearance intermediate to that of a bright sheet finish(e.g., a foil-like finish) and a standard can stock finish. Optionally,the dulled gloss finish can be characterized as having a “satin-gloss”appearance. Optionally, the dulled gloss finish can be characterized ashaving a non-mirror like appearance. Also, the dulled gloss surfacefinish has minimum directionality when compared with a traditionalrolled grit finish. The products having the dulled gloss surface finishdescribed herein have a low level of roughness such that subsequentprocessing can be improved. For example, less lacquer is needed forcoated products, such as can ends, and less customer material removaland processing (e.g., from lithography applications). Products preparedhaving the dulled gloss surface finish as described herein also exhibiteased manufacturability on standard rolling mills at high speeds andwith large reductions in sheet thickness.

The formability of products prepared having the dulled gloss surfacefinish is improved over that of material with a standard metal with a“directional” surface. The products with improved formability preparedusing the work rolls described herein are less prone to issues resultingfrom low formability, such as product cracking. Not to be bound bytheory, this is due, in part, to the fact that the friction in direction90° to the rolling direction is highest in the standard directionalmaterial. In the standard directional material, the forming loads areincreased due to direct impingement from the topographical peaks createdwith a standard roll ground surface. In the products described herein,the number of peaks is lowered by at least 10% over the standarddirectional material. For example, the number of peaks can be lowered byat least 20%, at least 30%, at least 40%, at least 50%, at least 60%, atleast 70%, at least 80%, at least 90%, or can be absent. Thus, thefriction is balanced in all directions and the extreme loads fromfriction at the 90° component are lowered. Moreover, when a circularproduct, such as a can end, is formed from standard directionalmaterial, the resulting shape is not a perfect circle, but is“off-drawn” into a subtle elliptical shape with the largest diameterbeing in the 90° direction. This is a direct result of the higherfriction (and hence higher forming load) in the 90° orientation. Theoperating window for forming can be widened with the surfaces describedherein to manage the “off-drawn” phenomena.

The dulled gloss surface finish, as described herein, has been developedto replace the rolled grit surface. A view of the surface structure ofthe dulled gloss finish is shown in FIG. 1, while a view of the surfacestructure of the rolled grit surface is shown in FIG. 2. The dulledgloss finish is desirable, for example, where more isotropy is required.

Method of Preparing Dulled Gloss Finish Work Roll

The work roll is made by smoothly finishing a roll before shot blastingit and subjecting it to a final polish. A roughened work roll for arolling mill made, for example, by sandblasting, can be polished tosmooth the upper peaks of the rough surface. The resulting sheet surfacecan contain a flattish base (i.e., a gloss) dulled by the residualroughness from the rough roll. Optionally, small micro-peaks randomlyscattered over the surface can remain. The finish can be generated athigh speed and with normal pass reductions in a cold mill.

In some embodiments, the surfaces described herein can be preparedaccording to a series of steps as described herein. The modifiedsurfaces are characterized herein by various parameters, including Raand Rz, which are measured in micrometers (microns) and are known tothose of skill in the art. Optionally, the parameters can be measuredusing the MountainsMap® Surface Imaging and Metrology software (DigitalSurf; Besancon, France). All roughness values can be mechanicallymeasured with a standard stylus. An unfinished work roll is used forpreparing the roll having the finish described herein. Unfinished workrolls appropriate for use can be obtained from a commercial source, suchas, for example, Steinhoff GmbH & Cie. OHG (Dinslaken, Germany) andUnion Electric Steel BVBA (Lummen, Belgium). The unfinished work rollcan be a metal roll, such as, for example, a steel work roll.Optionally, the unfinished work roll is a smooth work roll that does notcontain any scratch marks.

Grinding Step

The unfinished work roll is then ground, using a grit wheel, to form aground work roll. The unfinished work roll is ground until a targetroughness is achieved. The target roughness after the grinding step canbe characterized by an Ra of 0.2 μm or less. For example, the targetroughness in Ra after the grinding step can be 0.19 μm or less, 0.18 μmor less, 0.17 μm or less, 0.16 μm or less, or 0.15 μm or less. Thetarget roughness after the grinding step can be characterized by an Rzof 2.00 μm or less. For example, the target roughness in Rz after thegrinding step can be 1.80 μm or less, 1.60 μm or less, 1.40 μm or less,1.20 μm or less, or 1.00 μm or less. Suitable grit wheels for achievingthe target roughness in the work roll include 360 and below grit wheels.For example, suitable grit wheels include a 360 grit wheel, a 320 gritwheel, a 280 grit wheel, a 220 grit wheel, and a 180 grit wheel.

Superfinishing Step

The ground work roll is then polished, using a superfinisher, to achievean Ra of less than 0.015 μm and an Rz of less than 0.25 μm. For example,the Ra of the work roll after the superfinishing step can be 0.014 μm,0.013 μm, 0.012 μm, 0.011 μm, 0.010 μm, 0.009 μm, 0.008 μm, 0.007 μm,0.006 μm, 0.005 μm, 0.004 μm, 0.003 μm, 0.002 μm, or 0.001 μm. The Rz ofthe work roll after the superfinishing step can be less than 0.20 μm,less than 0.15 μm, less than 0.10 μm, or less than 0.05 μm. Suitablesuperfinishers include the Loser Model SF 100 (Waldemar Loser KGMachinenfabrik; Speyer, Germany) or a GEM 04150-M or 08150-CSuperfinisher commercially available from Grinding Equipment & MachineryCo. (Youngstown, Ohio). Following the superfinishing step, the surfaceof the roll can have a mirror-like appearance.

Roughening of the Roll

The roll can then be uniformly roughened to achieve an Ra of from 0.35μm to 0.45 μm and an Rz of less than 5 μm. For example, the Ra can be0.45 μm, 0.44 μm, 0.43 μm, 0.42 μm, 0.41 μm, 0.40 μm, 0.39 μm, 0.38 μm,0.37 μm, 0.36 μm, or 0.35 μm. The Rz of the roll following theroughening process can be less than 5 μm (e.g., less than 4.8 μm, lessthan 4.6 μm, less than 4.4 μm, less than 4.2 μm, less than 4.0 μm, lessthan 3.8 μm, less than 3.6 μm, less than 3.4 μm, less than 3.2 μm, orless than 3.0 μm). The roughening step can be performed using a gritblaster. Optionally, the grit blaster can include a 220 grit containingAl₂O₃ particles. In some examples, the preferred grit application andexhaust pressure and differential is from 2.5 bar to 4.5 bar. Theroughening step can optionally be performed using a shot peening method.As used herein, shot peening refers to impacting the surface of the rollwith particles using sufficient force to roughen the surface.

Final Finishing of the Roll

The roughened roll can then be finished using a polisher. Optionally, a9 μm graded abrasive film polishing band is used to polish the roughenedroll. The polisher can be passed over the roll up to four times (e.g., 1time, 2 times, 3 times, or 4 times) until the desired Ra and Rz valuesare achieved. The roll after the finishing step can have an Ra of from0.2 μm to 0.4 μm (e.g., from 0.22 μm to 0.37 μm, 0.25 μm to 0.35 μm, orfrom 0.27 μm to 0.3 μm). For example, the finished roll can have an Raof 0.2 μm, 0.21 μm, 0.22 μm, 0.23 μm, 0.24 μm, 0.25 μm, 0.26 μm, 0.27μm, 0.28 μm, 0.29 μm, 0.30 μm, 0.31 μm, 0.32 μm, 0.33 μm, 0.34 μm, 0.35μm, 0.36 μm, 0.37 μm, 0.38 μm, 0.39 μm, or 0.40 μm). The Rz of thefinished roll can be below 3 μm (e.g., below 2.5 μm). For example, theRz of the finished roll can be below 3 μm, below 2.9 μm, below 2.8 μm,below 2.7 μm, below 2.6 μm, below 2.5 μm, below 2.4 μm, below 2.3 μm,below 2.2 μm, below 2.1 μm, or below 2.0 μm. Optionally, a single usefilm polishing band is used to polish the roughened roll. In someexamples, a continuously rotating belt polisher or grinder is not used.

The roll can be used in a mill to produce the finish as describedherein. Optionally, one or both sides of the roll can be treated. Forexample, one or both sides of the roll can be treated using one or moreof the following steps: texturing, controlled surface modification,media blasting, chrome coating, and embossing. The final finished rollcan be analyzed using a Gardner Gloss meter as described in Example 1.The work roll as described herein (i.e., the final roll) can then beused for rolling processes, including cold rolling. For example, thefinal roll can be used in a mill that includes a cold roll step.Optionally, multiple work rolls as described herein can be used in amill. For example, two work rolls as described herein can be used tosimultaneously or tandemly finish both sides of a metal substrate.

Dulled Gloss Finish Products

Metal substrates can be cold rolled using the work rolls describedherein to prepare products having a dulled gloss finish. Optionally, themetal substrate can be an aluminum or aluminum alloy sheet. Optionally,the metal substrate can be a steel sheet. For example, the aluminumalloys can be alloys from the 1000, 3000, or 5000 alloy familiesaccording to the Aluminum Association Register.

The dulled gloss finish described herein is suitable for any productthat would benefit from a dulled gloss finish lacking strongdirectionality and having limited surface peaks (e.g., lithoapplications, can applications, and lacquer applications). For example,the dulled gloss finish described herein can be suitable for can ends,reflectors, painted and laminated products, signage, transportation,anodizing quality, and decorative finishes. In one embodiment, the canend is the end of a beverage can. An advantage of this finish is thatthere is a potential for saving coating weights since the roughness peakvolumes are reduced for a similar average transverse roughness.Optionally, the dulled gloss finish described herein can be suitable foraesthetic applications, including for electronics (e.g., externalsurfaces of electronics) and for other applications where visualreflection is desired. Exemplary electronics suitable for the dulledgloss finish include computers, cell phones, automobiles, notepads, andthe like.

The following examples will serve to further illustrate the presentinvention without, at the same time, however, constituting anylimitation thereof. On the contrary, it is to be clearly understood thatresort may be had to various embodiments, modifications and equivalentsthereof which, after reading the description herein, may suggestthemselves to those skilled in the art without departing from the spiritof the invention.

EXAMPLE 1

Reflection measurements and confocal microscopy were used to generatequantitative data from the following three finishes: bright rolledfinish, standard grit finish, and the dulled gloss finish (DGF)described herein. The data were analyzed to detect parameters thatnumerically distinguish the DGF finish from the other surface finishes.The visual appearance of the DGF finish is of a satin like gloss withminimal directionality, and significantly different from the usualrolled grit finish.

Experimental

Material was taken from the dulled gloss finish production series andcompared to both bright rolled surfaces and traditionally rolledsurfaces on similar products.

The dulled gloss finish (DGF) has been applied to AA1050 (as litho) andAA5182 (as Can End) alloys on whole coils with satisfactory uniformityand repeatability. Other 3000 series alloys have also been successfullyrolled as warm-up coils, without having taken any samples.

One finish that was produced was a mixture of a grit finish with the DGFoverlaid. This finish provided the dull sheen appearance, but wasvisually considered to be too directional, almost like the normal gritfinish, and thus was declared unsatisfactory for product use.

The material was at first analyzed with a Gardner Gloss meter at 20°,60° and 85° angles. The gloss measurement procedure adequately indicatesreflectivity differences for metals.

A sample of each surface was then analyzed with a Nanofocus confocalmicroscope to generate a height distribution of a representative surfacearea from which numerical surface parameters were generated.

Confocal Analysis Methodology

A 20× objective was used, giving a surface area of 0.8 mm×0.8 mm foranalysis. The raw measured surface data contained form and wavinesscomponents which had to be removed. There is no standardized way fordoing this on generalized 3D surfaces, and the procedure applied was asfollows: form removal by 2nd order polynomial, calculated for eachsurface individually (this removes any general large scale surfacecurvature); waviness removal by applying a robust Gaussian filter withcut off at 0.08 mm, and with edge management so that the resulting areawas still 0.8×0.8 mm² (this removes the smaller scale waves orundulations such that a flat roughness surface is left). This is thesurface used to compare to the equivalent rolled-grit or high-glossroughness surface.

The resulting roughness surface may still contain individual extremeexcursions caused by the measurement technique or dust, etc. These wereremoved by applying a threshold such that any upper and lower excursionswere removed approximately symmetrically about the median height levelleaving a 2 μm range of each sample for analysis. This was adequate forall the surfaces studied without having any significant feature removed.The points outside the thresholds were set as “missing data”.

RESULTS Optical Property Measurement

To measure distinctiveness (clarity) of image, the standard glossmeasurement was used in both parallel and transverse orientations to therolling direction. This indicates a difference in reflectance, and hencean indication of a) “glossiness” and b) anisotropy. The effect varieswith angle of incidence, so all three standard gloss measuring angleswere used (20°, 60°,85°). The gloss results for the variants are givenin Table 1 below.

TABLE 1 Alloy 20° 20° 60° 60° 85° 85° Sample (AA) parallel transverseparallel transverse parallel transverse Bresso bright 1050 1417 1409 717702 127 129 finish DGF 2009 12 1050 864 748 691 600 131 126 DGF 2011 07a1050 833 682 728 583 135 130 DGF CES 2012 5182 964 868 638 586 123 12606 a DGE 2009 10 1050 365 239 585 350 131 110 Rolled Grit 1050 337 187516 199 129 72.3 CES 2011 07 Rolled Grit 5182 295 162 487 186 121 86.3CES Backside

Confocal Microscopy Measurement

The confocal microscope surfaces generated the following data which wasanalyzed with the MountainsMap SARL Digital Surf software package(Besancon, France) using methods either commonly accepted or adhering tothe ISO standards. The confocally evaluated surface parameters after 2μm thresholding are shown in Table 2.

TABLE 2 Pro- Pro- jected jected area (%) area (%) No. Iso- above betweenof tropy Sa Sku 50% 25-50% Motif Sample (%) (μm) (−) height height PeaksBresso bright 33.3 0.03  24.3 10.7 89.2 122 finish DGF 2009 12 20.60.055 7.2 3.21 96.6 112 DGF 2011 22.2 0.056 7.24 6.17 91.1 473 07 a DGF2011 25 0.055 8.12 0.79 98.8 210 07 b DGF CES 24 0.055 10.3 0.91 98.6418 2012 06 a DGF CES 20 0.056 10.1 1.3 98.3 359 2012 06 b DGE 2009 102.75 0.105 5.25 16.2 83.5 120 Rolled Grit 2.08 0.185 5.36 14.5 79.4 203CES 2011 07 Rolled Grit 1.56 0.152 6.22 18 80.4 325 CES Backside RolledGrit 1.95 0.185 4.47 17 77 399 CES 2012 06

The isotropy function was zero for totally directional surface, and 100%for an isotropic surface. The parameter was generated from the surfaceFFT with thresholds of 5% (low) and 50% (high).

Sa and Sku are as defined in International Organization forStandardization (ISO) Standards 2517-28, and the projected areas arefrom a slice through the surface at two height positions, arbitrarilychosen as quartiles, 25% and 50% up from zero.

The motif maxima were taken from a waterfall analysis of the 3D dataassuming that points within 15% height threshold belong together.

Due to the differing surface structures, the motif numbers cannot becompared between the different categories.

DISCUSSION Optical Properties

The 20° gloss level shows that the finish lies between high gloss andstandard grit, both parallel and transverse to the rolling direction(see FIG. 3). DGF 2009 10, which is the DGF sample with visibly too muchrolling grit in its background behaves as the standard grit samples,which fits to a visual judgment.

The values at 60° angle are shown in FIG. 4. The anisotropy of thestandard grit finish is seen to be much more than that of the DGFwhereas the bright finish is effectively isotropic in gloss. FIG. 5,showing the ratio of the directions, also demonstrates this.

FIG. 5 shows that the DGF is behaving isotropically, like the brightfinish, with ratios near 1 and below 1.5, whereas the grit finishes arestrongly isotropic. The grit finish with DGF on top is behaving betweenthat of a bright sheet and that of a normal can finish. The 60° inparticular for this surface is not as anisotropic as the true gritfinish.

This comes out clearly at 85°, where the anisotropy of the rolled gritfinishes is still large, whereas the DGF on grit is nearer the true DGFfinish level without anisotropy (see FIG. 6).

Confocal Microscopy Parameters

The calculated isotropy of the surfaces is shown in FIG. 7. Thedifference between the 3 classes of bright, DGF, and rolled grit areclear, as they are in FIG. 8 for the average roughness (Sa) of thesurfaces.

The projected areas at the quartile positions give an indication of thematerial distribution over the surface. The Sku parameter is a similarparameter based on the width of the assumed normal distribution of theheights. These are shown in FIGS. 9 and 10, respectively. Depicting bothof these together leads shows a clearer separation, as is shown in FIG.11. In FIG. 11, the data points between 0 and 10 Sku and between 14-20%in projected area correspond to the rolled grit finish; the data pointsbetween 5 and 11 Sku and between 0 and 7% in projected area correspondto the trial surface, and the data point between 20 and 30 Sku andbetween 10 and 13% in projected area corresponds to the bright finish.These data demonstrate that the trial finish exhibits a flattish bottomwith a peaky top surface. Confocal images of the samples are shown inFIG. 12.

CONCLUSIONS

There are measurable differences between the bright finish, rolled gritfinish, and the new DGF finish that can be quantified. The 20° glosslies between 500 and 1100 units, well separated from both rolled gritand bright finish. At 60° the gloss anisotropy is half that of rolledgrit, and still separated in the transverse direction by >=200 units.The ratio of parallel to transverse gloss at both 20° and 60° angles iswell below 1.5, whereas grit finish is well above this. At 85°incidence, the DGF appears isotropic, like bright finish, whereas therolled grit finish is still anisotropic. Confocal microscopy shows thesurface frequency based isotropy to lie between 15% and 30%. Brightfinish is over 30% and grit finish below 5%. The Sa of the roughnesssurface shows DGF to be similar to bright and around 0.05 mm, well awayfrom the grit finished applied. The Sku and projected area above 50%height parameters are best judged against each other, giving clearboundary regions for the 3 surfaces.

All patents, publications and abstracts cited above are incorporatedherein by reference in their entirety. Various embodiments of theinvention have been described in fulfillment of the various objectivesof the invention. It should be recognized that these embodiments aremerely illustrative of the principles of the present invention. Numerousmodifications and adaptations thereof will be readily apparent to thoseskilled in the art without departing from the spirit and scope of thepresent invention as defined in the following claims.

1. A work roll, comprising: a surface having an Ra value of from 0.2 to 0.4 μm and an Rz value of less than 3.0 μm.
 2. The work roll of claim 1, wherein the surface has an Ra value of from 0.27 μm to 0.3 μm and an Rz value of less than 2.5 μm.
 3. The work roll of claim 1, wherein the work roll is a cold mill work roll.
 4. A method of preparing a work roll for applying a dulled gloss finish on a metal substrate surface, comprising: (a) roughening an unfinished work roll surface to form a roughened work roll surface, wherein the roughened work roll has an Ra of 0.20 μm or less and an Rz of 2.00 μm or less; (b) polishing the roughened work roll surface to form a polished work roll surface having an Ra of less than 0.015 μm and an Rz of less than 0.25 μm; (c) uniformly roughening the polished work roll surface to form a uniformly roughened work roll surface having an Ra of from 0.35 μm to 0.45 μm and an Rz of less than 5 μm; and (d) finishing the uniformly roughened work roll surface to form a work roll surface, wherein the work roll surface has an Ra value of from 0.2 to 0.4 μm and an Rz value of less than 3.0 μm.
 5. A work roll prepared according to the method of claim
 4. 6. A method of forming a dulled gloss finish on a metal substrate, comprising: (a) roughening an unfinished work roll surface to form a roughened work roll surface, wherein the roughened work roll has an Ra of 0.20 μm or less and an Rz of 2.00 μm or less; (b) polishing the roughened work roll surface to form a polished work roll surface having an Ra of less than 0.015 μm and an Rz of less than 0.25 μm; (c) uniformly roughening the polished work roll surface to form a uniformly roughened work roll surface having an Ra of from 0.35 μm to 0.45 μm and an Rz of less than 5 μm; (d) finishing the uniformly roughened work roll surface to form a work roll surface, wherein the work roll surface has an Ra value of from 0.2 to 0.4 μm and an Rz value of less than 3.0 μm; (e) inserting the work roll in a cold mill; and (f) cold rolling the metal substrate with the work roll to achieve the dulled gloss finish on the metal substrate.
 7. The method of claim 6, wherein the metal substrate is aluminum or an aluminum alloy sheet.
 8. A product formed according to the method of claim
 6. 9. The product of claim 8, wherein the product is a can end.
 10. The product of claim 8, wherein the product is a surface of an electronic product.
 11. The product of claim 8, wherein the product is a surface for lithographic use. 